A few years ago I learned that the term for when the leaves start coming out is the "leaf-out." That simple little name tickles me every spring now. If you want to know more about the leaf-out, check out Signs of the Seasons - they're conducting a leaf-out study and you can participate.
I've been watching this tree outside my bedroom window sprout little green flower-clusters for about four days now. I think it's an oak, but I'm not sure. It was the last tree around our driveway to lose its leaves last year, and now it's the first one to show some spring initiative! A few trees are in flower around here, but most are still ramping up their buds. I saw some honest-to-goodness baby leaves spilling out of their bud-casings today, on a different tree right in my own driveway. Pretty soon we will lose our great view of Boston, but it is totally worth it to see green everywhere for a few months!